Idle issues...

Could use any input/information on a problem my E39 has had for quite a while (and nobody seems to know why!! ). It has to do with idling, especially in the first 5-10 minutes of driving.

Here's the deal: In the morning, especially here in the wintertime in the Northeast, I start the car and let it "warm up" for about 5-10 minutes or so. Then, once I start to back out of the driveway, I have to wait for any passing cars. While waiting, the tach needle bounces up and down between 1000 RPMs and, let's say, around 500 or so...up and down. The car feels as if it's going to stall, and at this point I wish I had 3 feet...one each for the brake, clutch, and the gas to keep it from stalling. A mile from my home is a stop sign, and while waiting for my chance to go, it happens then. This will happen another 2 times or so on my trip, until I get onto the highway.

I have mentioned this to my mechanic several times and they don't notice any reason for this...no codes, no noticeable air/vacuum leaks, nothing. Even a trip to the dealership produced no noticeable causes from their service advisers. Just so we're clear, this car has had a new radiator installed, all new oil gaskets, new oil separator and VANOS "stuff" installed...lots of things. The car runs and drives like a dream...I have suffered no loss of gas mileage or power at all.

Have any of you E39 drivers had similar issues to this? Is this a known issue with these cars and if so, what could be causing it?

How about spark plugs...my 540iA owners manual says replace the plugs at 100k. After over 10 years of service life (and about 101,000 miles) I started to notice drive-ability issues, especially lower rpm gear shifts. New Bosch plugs around ($6 each) solved the problem that I was worried would be big $$$. (BMW plugs for the 8 were around $20 each not too long ago, BavAuto has a less costly and guaranteed option now, plugs installed back in Oct 2011).

The manual also recommends NOT warming up the engine. Start driving immediately. I warm it up for about 15 seconds, then take it easy for a mile or two...

It could be bad fuel too. Try BMW fuel treatment. I used off the shelf ISO heat once and the engine lights came on. Bad idea. The car acted strange for a tank or two...

How about spark plugs...my 540iA owners manual says replace the plugs at 100k. After over 10 years of service life (and about 101,000 miles) I started to notice drive-ability issues, especially lower rpm gear shifts. New Bosch plugs around ($6 each) solved the problem that I was worried would be big $$$. (BMW plugs for the 8 were around $20 each not too long ago, BavAuto has a less costly and guaranteed option now, plugs installed back in Oct 2011).

Hmmm...never thought of that. Next time she's in for service I'll ask about the plugs.

The manual also recommends NOT warming up the engine. Start driving immediately. I warm it up for about 15 seconds, then take it easy for a mile or two...

I tried experimenting with that this week and that seems to do the trick. The only problem with this will be the however many days we could have left when there's frost or ice on the windshield, and I absolutely HAVE to warm 'er up!

It could be bad fuel too. Try BMW fuel treatment. I used off the shelf ISO heat once and the engine lights came on. Bad idea. The car acted strange for a tank or two...

If the fuel were the problem, wouldn't the performance of the engine suffer all the time and not just first thing in the morning or first drive? Plus I've been dealing with this issue for quite some time...and I would be hard-pressed to think that every tank of gas I've gotten at every station I've used were bad...but I AM in NJ after all, so it wouldn't surprise me...LOL!

You are right about the fuel, however it may mix itself up after you start moving and the problem goes away after the engine burns off (or tries to) the condensation. They say that fuel treatment helps you remove the water build up and burn it off...see what your mechanic says. Good luck, what is your mileage on your spark plugs?

It is a classic. Vanos seals. The problem will gradually get worse but slowly. It is a complicated job not for a novice, but do-able for the adventurous.

Hey guys...thanks for the input but you're a little shy of 6 months too late - I traded 'er in back in June for a sweet '06 330i 6-speed manual with sport package. Besides the idle issues it was using oil at a crazy pace.

Precisely the same thing happened with my 2000 540i. It was a vacuum leak at the intake manifold seals which deteriorate due to the high heat level of this engine and the very squishy gaskets themselves. It only happened at the warm-up stage and only then, at idle. Got worse with the coldness of the night temparature (temperature of engine at start-up). Since the manifold is plastic it cannot be torqued down very tight (purposely limited by bolt design in fact) and relies instead on the compressibility of the gasket material. Job took 8 hrs at home. Gaskets cost $27.00 per side. Solved completely.